ImageMagick uses several freely available packages to perform the
translation of certain image formats (PostScript, PICT, etc.).
Make sure these packages are available as described in the
README
file. Also verify that you have plenty of temporary disk space.
If not, set the TMPDIR environment variable to an area where space
is available. Finally, for PostScript, verify that Ghostscript
supports the pnmraw or ppmraw device (gs -h) and that
the document contains valid PostScript statements (gs image.ps).

If you have a colormapped X server, the number of unique colors in
an image must first be reduced to match the requirements of your
server before it can be displayed. Display tries to make the
color reduced image closely resemble the original. However, there
are some options that may improve the appearance.

You can use a private colormap. By default, your image must share
colors with existing applications on your X server. The colors in
your image may be very different than the shared colors and the
results may be visually unsatisfactory. Try

display -colormap private image.miff

The disadvantage is the annoying colormap loading and unloading as
you move your pointer in and out of the image window.

The YCbCr colorspace may give better results when color reducing
images of people faces. Try

display -colorspace YCbCr image.miff

If you intend to view an image frequently, reduce the number of
colors to match the resolution of your X server once and write to a
new image. Then display this new image. For example,

convert -colors 256 -dither image.jpeg image.miff
display image.miff

This forces the time-consuming process of color reducing the image
to one-time, rather than each time the image is displayed.

Display your GIF image with display. Choose
Matte from the Image Edit command menu and identify a pixel
that has the transparency color. Press Method and select a
matte edit method from a pop-up menu. Choose from these methods:

point
replace
floodfill

The point method changes the matte value of any pixel selected with
the pointer until the button is is released. The replace method
changes the matte value of any pixel that matches the color of the
pixel you select with a button press. Floodfill changes the matte
value of any pixel that matches the color of the pixel you select
with a button press and is a neighbor.

Select your transparent pixel with the pointer and press a button.
The image is redisplayed with any transparent pixels recolored to
the background color. You can select other pixels or areas to
force to transparent. When you are satisfied, press Return.

Finally, choose Save from the command menu and write your GIF
image to a file. Note that setting transparency works best on a
TrueColor or DirectColor visual. If your server only exports
colormapped visuals you will need to use a Standard Colormap to set
transparency.

By default, import quickly grabs
the image from the X server. However,
it may not always have the correct colors
in some areas. This can happen when a subwindow has a
different colormap than its parent. With -descend,
import
descends the window hierarchy. Descending involves
grabbing the image and colormap of each window or subwindow
associated with the window you select and compositing it on
a blank canvas. This can be significantly slower than just
grabbing the top-level window but ensures the correct image.

The simplest thing to do is to increase your virtual memory by
expanding your swap partition.

ImageMagick is designed to be general purpose. It can display many
image storage formats (Monochrome, PseudoColor, or
TrueColor) on many different types of X visuals (StaticGray,
StaticColor, PseudoColor, GrayScale, DirectColor, or TrueColor).
To support all these combinations of image storage formats and X visuals, extra
memory is required. In fact, each image requires up to 6 bytes per pixel
to store in memory. Additionally, animate and montage store an entire image
sequence in memory.

For animation, consider using the MPEG programs from Berkeley if
you encounter memory limitations with animate.
It only stores a few frames at a time in memory. Convert has an option to create the
proper CCIR 601 2:1:1 files as input to the MPEG program. However, the
CCIR 601 2:1:1 image format is lossy. Computer generated images may not
look very good.

ImageMagick automatically trims any PostScript image as
defined by the bounding box. To preempt this behavior, remove the bounding
box statement from the Postscrpt or explicitly set the
page size. For example,

A visual image directory (VID) is an image that contains thumbnails
of one or more images in a file directory. Rather than displaying
each individual image at its full resolution, you can browse the
visual image directory and choose an image to display. You can
create a VID with either of these commands:

montage *.jpg directory.vid
convert 'vid:*.jpg' directory.vid

Of course you can substitute any filenames you desire. Montage has many relevant command
line options. You can exercise more control over the appearance of the VID
than with convert.

Next display the directory:

display directory.vid

Finally browse and select an image to display. Move the pointer to
the image and press button 3.

You can create the VID directory with this command:

display 'vid:*.jpg'

You can also select Visual Image... from the File menu of the
command widget.

Note, that creating a VID is time consuming. Creating them
on-the-fly within display may be
less convenient than using montage or convert . Also, if you create them
with montage. or convert, you can reuse them as often
as necessary.

Note that a visual image directory is useful for looking at
individual frames of an image sequence:

A blank image generally means that the image is either corrupt or
it has a matte channel and the matte values are all zero.
ImageMagick treats a matte value of zero as completely
transparent. To determine if this is the problem, try

ImageMagick requires source libraries not included with the
distribution to view or convert certain image formats such as JPEG
or TIFF. The above message means you did not compile the required
library and link with the ImageMagick utilities. See
README
for the location of these libraries and
compiling instructions. Also edit Magick.tmpl
if you use xmkmf or Makefile.in if you use
configure and uncomment the appropriate plug-in defines as
instructed. Finally, type

LZW compression is no longer available in the ImageMagick
distribution (GIF pixel data is saved uncompressed). I am in
agreement with
L. Peter Deutsch's arguments
regarding LZW within Ghostscript:

Unisys claims that they have the right to demand licenses
and/or fees from free software incorporating the LZW algorithms,
even though they are currently not doing this. This will hang
over the head of the developer of any free software that creates
GIF files until the Welch patent expires on December 10, 2002
(17 years after its award date).

I wish to support the industry move from GIF to PNG. The next
Aladdin Ghostscript release (and possibly the next GNU
Ghostscript release as well) will include PNG drivers;
experimental PNG drivers for Ghostscript are already available.
More generally, I wish to support any industry move away from
reliance on patented software, which my studies have led me to
consider a bad deal for everyone except a few lawyers and a few
very large companies.

While Unisys' press release says they will not seek licenses or
fees from "non-commercial, non-profit" distributors, it is not
at all clear to me that they would also exempt people like
Walnut Creek CD-ROM, FSF, or Yggdrasil, who distribute free
software but charge for the media and documentation. FSF and
Yggdrasil, at least, would not redistribute GIF code under those
circumstances. This would have a very bad effect on the
availability of Ghostscript. I also believe, given that
CompuServe gave in to Unisys' demands, that Unisys might demand
licenses and fees from any commercial ISP (Netcom, AOL, ...)
that distributed free software containing LZW code.

Unisys' conditions are not compatible with
the GNU License, since they restrict recipients' rights.

A kit is available to enable LZW compression for GIF, Postscript Level
II, and the Portable Document Format within ImageMagick from
ftp.wizards.dupont.com .

Note, this kit may not be redistributed. This service may be
discontinued at any time.